Enterprise cognitive radio integrated with laser communications

ABSTRACT

A wireless data access system is provided to ameliorate bursty traffic occurring in a radio communications link such as a WiFi, WiMAX, 3G or cellular telephone link to a wireless network access device. A data traffic event is detected relating to traffic in the link. The traffic event may be a traffic burst exceeding a predetermined threshold. Based on detecting the data traffic event, a free-space optical communications link is established to the network access device to handle the traffic burst. The established radio link may be used to set-up and coordinate the free-space optical link.

FIELD OF THE INVENTION

The present invention relates generally to wireless data access systems,and more particularly to a technique for exchanging highly burstablefiles/media/data on an as-needed basis, using free-space opticalcommunications coordinated by a radio control/synchronization channel.

BACKGROUND OF THE INVENTION

Independent wireless network access devices often operate in a cell,“hotspot” or situation in which the access device competes with otheraccess devices for banadwidth, connection time and other resources. Thatcondition may limit speed and Quality of Service (QoS) in situationswhere the access device is required to perform a “bursty” operation suchas the downloading of a large file. Such “bursty traffic may also causeinterference with the connections of other network access devices, causechannel over-utilization and increase power consumption of the networkaccess device.

For example, local area wireless networks are being deployed inincreasing numbers to bring broadband services to greater numbers offixed, ambulatory and mobile users. Those wireless local area networkare often used to download email with attachments, media files and otherdata-intensive operations. As “bursty” network usage becomes morecommon, it has become a significant challenge to maintain QoS andprovide greater bandwidth capabilities to increasing numbers ofcustomers.

A paradigm called “cognitive radio” has been used in wireless networksto ameliorate the above described problem. A cognitive radio systemchanges particular parameters of radio transmission or reception ineither the network or a particular wireless node, based on theobservation of various parameters in the radio environment. For example,transmissions may be shifted from one radio frequency to another withinthe allowed spectrum, based on observed atmospheric conditions andinterference from other local transmitters. Other radio transmissionparameters may also be adjusted to optimize transmission, given theenvironmental conditions, user behavior, network state, or otherfactors.

While cognitive radio principles have been used with some success inmore efficiently using RF bandwidth within a wireless network such as acellular telephone network, a 3G radio network or a WiFi network, suchtechniques are limited by the amount of RF bandwidth available under FCCregulations. If a data burst requires bandwidth beyond that which can beprovided over the available RF frequencies, a bottleneck occurs.

There is therefore a need for a system that is capable of handling largebursts of data without degrading transmission speed or QoS. The systemshould not require RF spectrum beyond that which is available for theparticular wireless technology used in the system.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above in a methodfor providing wireless network services. The method comprises the stepsof establishing a first communications link to a network access device,detecting a data traffic event relating to traffic in the link, and,based on detecting the data traffic event, establishing a free-spaceoptical communications link to the network access device.

The method may further include the step of coordinating the free-spaceoptical communications link using the first communications link. Thestep of coordinating the free-space optical communications link mayfurther include passing session management information, or passing GPSlocation information, or passing beam timing information.

The first communications link may be a radio communications link. Theradio communications link may be an IEEE 802.11x-compliant radio link.The link may be selected from a group consisting of WiFi, WiMAX and 3Gradio links. The radio communication link may alternatively be acellular telephone link.

The step of detecting a data traffic event may include detecting athreshold minimum traffic level, or may include detecting a metricrelating to power consumption.

In another embodiment of the invention, a network access point isprovided for coordinating communication among network access devices ina network. The access point includes a processor, a radio transceiverconnected to the processor for establishing a radio link with a firstnetwork access device, a free space optical transceiver connected to theprocessor for establishing a free space optical link with the firstnetwork access device, and a computer readable medium accessible by theprocessor and containing instructions. Those instructions, when executedby the processor, cause the processor to monitor the radio link with thefirst network access device for a traffic event, and, based on anoccurrence of a traffic event, to cause the processor to establish afree space optical connection through the free space optical transceiverto the first network access device.

The computer readable medium may further contain instructions that, whenexecuted by the processor, cause the processor to coordinate thefree-space optical communications link using the radio link. Theprocessor may coordinate the free-space optical communications linkusing the radio link by passing session management information, or bypassing beam timing information. The processor may coordinate thefree-space optical communications link using the radio link based atleast in part on GPS location information.

The radio link may be an IEEE 802.11x-compliant radio link, and may beselected from a group consisting of WiFi, WiMAX 3G and cellulartelephone radio links.

The computer readable medium may further contain instructions that, whenexecuted by the processor, cause the processor to monitor the radio linkwith the first network access device for a traffic event by detecting athreshold minimum traffic level, or by detecting a metric relating topower consumption.

Another embodiment of the invention is another method for providingwireless local area network services. The method includes the steps ofestablishing a first communications link between a first network accessdevice and a second network access device, detecting a data trafficevent relating to traffic between the first and second network accessdevices, and, based on detecting the data traffic event, establishing afree-space optical communications link between the first and secondnetwork access devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a system according to oneembodiment of the invention.

FIG. 2 is a schematic representation of an FSO transceiver unitaccording to one embodiment of the invention.

FIG. 3 is a flow chart representing a method according to one embodimentof the invention.

DESCRIPTION OF THE INVENTION

The present invention overcomes the above-described problems byproviding a technique and apparatus for use in a wireless networkwhereby, upon detection of a data traffic event such as a burst in datavolume, a free space optical connection is established to absorb some orall of the traffic volume. The original wireless connection may be usedto coordinate the free space optical connection.

An exemplary wireless network system 100 in accordance with theinvention is shown in FIG. 1. Network access devices 140 and 150 accessthe network through an access point 120. For example, in an IEEE 802.11wireless network, the network access devices 140, 150 establish radiocommunication links 161, 162, respectively, with the network accesspoint 120. The access device 140 includes a radio transceiver 141 forcommunicating with a radio transceiver 125 in the access point 120.Similarly, access device 150 includes a radio transceiver 151.

The access point 120 includes a central processing unit (CPU) 121, mainmemory 123 and storage media 124, interconnected by a system bus 122.The media stores instructions that are loaded into main memory, and areexecuted by the CPU to perform tasks in accordance with the invention.

The access point 120 further comprises the radio transceiver 125 asdiscussed above, and a network interface 127 for connecting with anetwork 130 such as the Internet.

In accordance with the invention, the network access devices 140, 150also include or have access to free space optical (FSO) transceivers142, 152, respectively. The access point 120 also includes an FSOtransceiver 126.

An exemplary FSO transceiver unit 200 is shown schematically in FIG. 2.That FSO transceiver unit comprises both a transmitter unit 210 and areceiver unit 240. The transmitter unit 210 includes one or more lenses212 (or equivalent lens and mirror configurations), that are designed totransmit modulated optical energy received either from an optical fiber213 attached to a suitable laser or LED source 214, or directly from alaser or LED source located at or near the focus of the lens. Theoptical modulation of the free space optical link utilizes methods thatare well demonstrated in the art in such applications as “radio onfiber” or hybrid fiber/radio (HFR). For example, the output of thetransceiver transmitter 210 may be amplitude modulated, thus replicatingin the optical domain the 802.11 radio transmission. In that case, an “Rto O” or “Radio signal to Optical signal” module 216 feeds the FSOtransmitter 210. Similarly, the optical modulator may be capable ofconverting electronic signals or wired network link technology such asthe Ethernet to optical signals, shown schematically in FIG. 2 as “E toO” module 218. In some designs, a single device (not shown) mayaccomplish both types of modulations. The transceiver “transmitter” lens212 or lens array will receive that modulated optical energy from itssource and reconfigure the optical energy into a beam 220 with aselectable divergence angle 222 suitable for transmission of this beamthrough the air to a distant receiver.

The receiver unit 240 comprises a lens, lens array and/or mirrorconfiguration 242 designed to collect the transmitted and modulatedoptical energy from a distant transmitter unit and focus that collectedenergy onto a suitable transceiver “receiver” photodiode 244. Theoptical signal is demodulated back into the electrical domain by anoptics-to-electronics conversion module 246 or an optics-to-radioconversion module 248.

In a preferred embodiment of the invention, the FSO transceiver assembly200 uses beam steering and track methods to maintain link alignment. Amotion mount 260 allows for independent position alignment for FSO linkreconfiguration considerations. Such beam steering and tracking devicesare available, for example, from Omnilux Inc. and from AirFiber of SanDiego, Calif.

With the ability to transmit 802.11 RF signals directly in the opticaldomain, data traffic can be transmitted directly from network accessdevice to network access device, as represented by optical beam 171(FIG. 1), or from a network access device to a network access point, asrepresented by optical beam 172. The FSO access point may be the sameaccess point used for radio communications in the network, or may be adifferent access point.

As illustrated in FIG. 3, an exemplary method 300 in accordance with theinvention begins with establishing (step 310) a first communicationslink to a network access device. In a preferred embodiment of theinvention, the first communications link is a radio link such as a WiFi,WiMAX, 3G and cellular telephone radio link.

The link is monitored (step 320) for a traffic event relating to trafficin the link. In one embodiment of the invention, the link is monitoreddirectly through a tap, and a minimum number of bits per second oranother traffic volume measurement triggers a traffic event.Alternatively, another element reflective of current or imminent dataflow in the link is monitored. For example, an outgoing data buffer maybe monitored and a traffic event detected when the data buffer reaches acertain size. In another example, file requests are monitored and atraffic event is triggered when a file of a threshold size is requestedor is about to be sent, or when a threshold quantity of data isrequested within a predetermined time period. The data traffic may bemonitored by the processor 121 in the access point 120 (FIG. 1) or froma processor (not shown) in the network access device 140. Other datatraffic monitoring schemes will be apparent to those skilled in the art.

Upon detection of a traffic event (decision 330), a free-space opticalcommunications link is established (step 340) for carrying some or allof the traffic exchanged between the devices connected by the firstcommunications link. In a preferred embodiment, the FSO link iscoordinated (step 350) using the first communications link. For example,the FSO link set-up may be coordinated by an existing radio link betweenthe access point 120 and the network access device 140.

The coordination may include transmitting GPS location information forthe access device 140, the location information being obtained from aGPS receiver 143 associated with the device. Through database lookupengines, it is possible to determine, based on GPS coordinate data, thelocations of various access points available to an end device. Inaddition, the GPS data reveals where the end devices are, for routeoptimization and policy enforcements based on locations. Physical beamaiming may be assisted based on GPS data and the known location data ofan access point.

Beam aiming, beam synchronization and other physical protocols, as wellas upper layer protocols, may be implemented through coordination usingthe radio link. Beam aiming is preferably accomplished through peer topeer protocol, assuming that routing optimization can be done by thenetwork. In ad hoc networks, the end devices must execute a thinprotocol to synchronize the FSO beams at each other.

The system of the invention may furthermore monitor data traffic(decision 360) to determine the point at which the FSO link is no longernecessary. The FSO link is then disconnected (step 370) and the systemreturns to monitoring for a data traffic event (step 320).

The optical channel is preferably utilized in the system of theinvention for terminal policies. For example, in an airport environment,as planes are about to take off, or immediately after they land, theremay be significant bandwidth overload due to spectrum limitation in thearea. FSO can be used to upload or download the personal media of thepassengers on the plane. The amount of data may be so massive that radiowill not support it. An active, synchronized FSO channel under thosecircumstances is capable of handling the resulting burst of data.

The inventive system has many advantages over a cognitive radio. Forexample, depending on the environment in which the system is being used,interference among radio channels may be greatly reduced. Further,channel usage is optimized. In a large metropolitan area, traffic modelsmust currently accommodate bursty traffic patterns, using store andforward techniques.

Power management is greatly enhanced in handheld network access devicessuch as cell phones, PDAs and laptops. In current systems, significantpower is consumed in channel scanning to find an available path for databursts. The present invention eliminates that need because each networkaccess device can access an access point with high bandwidth on demand.For example, email inboxes with attachments may be downloaded withoutmonitoring radio frequencies for an available channel.

The foregoing Detailed Description is to be understood as being in everyrespect illustrative and exemplary, but not restrictive, and the scopeof the invention disclosed herein is not to be determined from theDetailed Description, but rather from the claims as interpretedaccording to the full breadth permitted by the patent laws. For example,while the method of the invention is described herein primarily withrespect to use with wireless radio systems incorporating the IEEE 802.11MAC protocol standard, the method and apparatus of the invention may beused in conjunction with access points using other access controlstandards such as wireless cellular telephony. It is to be understoodthat the embodiments shown and described herein are only illustrative ofthe principles of the present invention and that various modificationsmay be implemented by those skilled in the art without departing fromthe scope and spirit of the invention.

What is claimed is:
 1. A method performed in a wireless access point forproviding wireless network services, the method comprising: establishinga first communications link between a first network access device and asecond network access device via the wireless access point, the firstand second network access devices being independent wireless networkaccess devices, the first communications link comprising a firstwireless radio link between the first network access device and thewireless access point, and a second wireless radio link between thesecond network access device and the wireless access point; detecting atthe wireless access point a data traffic event relating to traffic inthe first communications link; based on detecting the data trafficevent, establishing a direct free-space optical communications link fromthe first network access device to the second network access device, thedirect, free-space optical communications link bypassing the wirelessaccess point; and at the wireless access point, coordinating the direct,free-space optical communications link between the first network accessdevice and the second network access device, the coordinating using thefirst wireless radio link between the first network access device andthe wireless access point, the coordinating further using the secondwireless radio link between the second network access device and thewireless access point.
 2. The method of claim 1, wherein coordinatingthe free-space optical communications link further comprises passingsession management information.
 3. The method of claim 1, whereincoordinating the free-space optical communications link furthercomprises passing GPS location information, and aiming a beam carryingthe free-space communication link using the GPS location information. 4.The method of claim 1, wherein coordinating the free-space opticalcommunications link further comprises passing beam timing information.5. The method of previously presented claim 1 wherein the radiocommunications link is an IEEE 802.11-compliant radio link.
 6. Themethod of claim 1 wherein the radio communications link is a radio linkselected from a group consisting of WiFi, WiMAX, 3G and cellulartelephone radio links.
 7. The method of claim 1 wherein detecting a datatraffic event comprises detecting a threshold minimum traffic level. 8.The method of claim 1 wherein detecting a data traffic event comprisesdetecting a metric relating to power consumption.
 9. A non-transitorycomputer-usable medium having computer readable instructions storedthereon for execution by a processor to perform a method performed in awireless access point for providing wireless network services, themethod comprising: establishing a first communications link between afirst network access device and a second network access device via thewireless access point, the first and second network access devices beingindependent wireless network access devices, the first communicationslink comprising a first wireless radio link between the first networkaccess device and the wireless access point, and a second wireless radiolink between the second network access device and the wireless accesspoint; detecting at the wireless access point a data traffic eventrelating to traffic in the first communications link; based on detectingthe data traffic event, establishing a direct free-space opticalcommunications link from the first network access device to the secondnetwork access device, the direct, free-space optical communicationslink bypassing the wireless access point; and at the wireless accesspoint, coordinating the direct, free-space optical communications linkbetween the first network access device and the second network accessdevice, the coordinating using the first wireless radio link between thefirst network access device and the wireless access point, thecoordinating further using the second wireless radio link between thesecond network access device and the wireless access point.
 10. Thenon-transitory computer-usable medium of claim 9, wherein coordinatingthe free-space optical communications link further comprises passingsession management information.
 11. The non-transitory computer-usablemedium of claim 9, wherein coordinating the free-space opticalcommunications link further comprises passing GPS location information,and aiming a beam carrying the free-space communication link using theGPS location information.
 12. The non-transitory computer-usable mediumof claim 9, wherein coordinating the free-space optical communicationslink further comprises passing beam timing information.
 13. Thenon-transitory computer-usable medium of claim 9, wherein the radiocommunications link is an IEEE 802.11-compliant radio link.
 14. Thenon-transitory computer-usable medium of claim 9, wherein the radiocommunications link is a radio link selected from a group consisting ofWiFi, WiMAX, 3G and cellular telephone radio links.
 15. Thenon-transitory computer-usable medium of claim 9, wherein detecting adata traffic event comprises detecting a threshold minimum trafficlevel.
 16. The non-transitory computer-usable medium of claim 9, whereindetecting a data traffic event comprises detecting a metric relating topower consumption.